Design and Fabrication of A High Density Metal Microelectrode Array for Neural Recording

Abstract We report a new fabrication technique for realizing a high-density penetrating metal microelectrode array intended for acute multiple-unit neural recordings. The microelectrode array consists of multiple metal shanks projecting from a silicon supporting bulk. Neural recording sites, separated by an average spacing of 50 μm, are located at the tip of each shank. Each shank is comprised of two segments to realize both mechanical strength and sharp tissue penetrating ability. A rear support segment is 6 mm long, 40 μm wide, and 30 μm thick. The front segment consists of a 250 μm long and 6 μm thick tapered tip, with the width at its widest point being 15 μm. Electrical insulation of the microelectrode body is achieved by a conformal coating of a 3 μm thick poly( para -chloroxylylene) (Parylene-C) film. Multiple recording sites with precise opening sizes are defined by selectively removing Parylene-C from the electrode tips using photolithography and oxygen plasma etching.

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